BEIJING, July 13 (Reuters) – China’s aluminium exports exceeded half a million tonnes for only the second time ever in June as stronger international than domestic prices encouraged overseas shipments, while steel exports hit an 11-month high, defying U.S. tariffs. China is the world’s biggest producer of both steel and aluminium, which have been subject to 25 percent and 10 percent import tariffs, respectively, in the United States, the world’s largest economy, since March 23. Unwrought aluminium and aluminium product exports were 510,000 tonnes last month, China’s General Administration of Customs said on Friday.. That was up 10.9 percent from 460,000 tonnes a year ago. Exports also topped a revised 480,000 tonnes in May, which was previously the second-highest figure on record behind only the whopping 542,700 tonnes exported in December 2014. Exports for the first half of the year were at 2.713 million tonnes, up 12.8 percent from 2.405 million tonnes a year earlier, customs said. Meanwhile, steel product exports for June climbed 1.9 percent year on year to 6.94 million tonnes, hitting their highest since July 2017. Exports were up 0.9 percent from 6.88 million tonnes in May. For the first half, steel exports were 35.43 million tonnes, down 13.2 percent year on year, customs said.